U.S. patent application number 11/228419 was filed with the patent office on 2006-03-23 for manufacturing method of a semiconductor device.
This patent application is currently assigned to DongbuAnam Semiconductor Inc.. Invention is credited to Han-Choon Lee.
Application Number | 20060063395 11/228419 |
Document ID | / |
Family ID | 36074634 |
Filed Date | 2006-03-23 |
United States Patent
Application |
20060063395 |
Kind Code |
A1 |
Lee; Han-Choon |
March 23, 2006 |
Manufacturing method of a semiconductor device
Abstract
A method of manufacturing a semiconductor device employs a PEALD
method including using an organometallic Ta precursor to form a TaN
thin film. As a result, a conformal TaN diffusion barrier may be
formed at a temperature of 250.degree. C. or higher, so that
impurities are reduced and density is increased in the TaN thin
film.
Inventors: |
Lee; Han-Choon; (Seoul,
KR) |
Correspondence
Address: |
THE LAW OFFICES OF ANDREW D. FORTNEY, PH.D., P.C.
7257 N. MAPLE AVENUE
BLDG. D, SUITE 107
FRESNO
CA
93720
US
|
Assignee: |
DongbuAnam Semiconductor
Inc.
|
Family ID: |
36074634 |
Appl. No.: |
11/228419 |
Filed: |
September 15, 2005 |
Current U.S.
Class: |
438/785 ;
257/E21.168 |
Current CPC
Class: |
C23C 16/45542 20130101;
C23C 16/50 20130101; H01L 21/28568 20130101; C23C 16/34
20130101 |
Class at
Publication: |
438/785 |
International
Class: |
H01L 21/31 20060101
H01L021/31; H01L 21/469 20060101 H01L021/469 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 17, 2004 |
KR |
10-2004-0074498 |
Claims
1. A method of manufacturing a semiconductor device, comprising:
forming a substrate having a plurality of predetermined structures
therein and/or thereon; and forming a TaN thin film from a Ta
precursor by plasma-enhanced atomic layer deposition (PEALD), using
a plasma gas comprising a hydrogen source.
2. The manufacturing method of claim 1, wherein forming the TaN
thin film comprises depositing the precursor and/or forming the TaN
thin film at a temperature higher than 250.degree. C.
3. The manufacturing method of claim 3, wherein the organometallic
tantalum compound has the formula
Ta(NR.sub.2).sub.x(.dbd.NR).sub.y, where R is an alkyl group and
(x+2y)=5.
4. The manufacturing method of claim 1, wherein the Ta precursor
comprises pentakis(ethylmethylamino)tantalum (PEMAT),
tertbutylimido(trisdiethylamide)tantalum (TBTDET),
pentakis(diethylamide)tantalum (PDEAT), or
pentakis(dimethylamide)tantalum (PDMAT).
5. The manufacturing method of claim 1, wherein the plasma further
comprises a nitrogen source.
6. The manufacturing method of claim 1, wherein the hydrogen source
comprises H.sub.2 gas.
7. A method of manufacturing a semiconductor device comprising the
steps of: purging a reactor and a gas line; injecting a Ta
precursor in a reactor; purging the reactor and the gas line again;
supplying a hydrogen source gas by opening a first gas valve
connected to the reactor and the gas line; and forming a TaN thin
film by supplying plasma power to the reactor.
8. The method of claim 7, further comprising stopping a supply of
plasma power and of the hydrogen source gas.
9. The method of claim 7, wherein the precursor comprises
pentakis(ethylmethylamino)tantalum (PEMAT),
tertbutylimido(trisdiethylamide)tantalum (TBTDET),
pentakis(diethylamide)tantalum (PDEAT), or
pentakis(dimethylamide)tantalum (PDMAT).
10. The method of claim 7, wherein the purging steps are
respectively performed for 1 to 3 sec.
11. The method of claim 7, wherein the plasma power is supplied for
a length of time of from 11 to 13 sec.
12. The method of claim 7, further comprising supplying a nitrogen
source to the reactor.
13. The method of claim 7, wherein the TaN film is formed at a
temperature of 250.degree. C. or higher.
14. The method of claim 7, further comprising forming a metal line
on the TaN thin film.
15. The method of claim 14, wherein the metal line comprises
copper, aluminum, or tungsten.
16. The method of claim 15, wherein the metal line comprises copper
and the method further comprises: depositing a seed copper layer on
the TaN thin film; and forming the copper line on the seed copper
layer.
17. The method of claim 16, wherein the seed copper layer is formed
by PVD.
18. The method of claim 15, further comprising: depositing Ta on
the TaN thin film; depositing a seed copper layer on the Ta; and
forming a copper line on the seed copper layer.
19. The method of claim 18, wherein depositing the seed copper
layer comprises a PVD method, an ALD method, or a CVD method.
20. The method of claim 15, wherein the semiconductor device is on
or in a substrate a dual damascene and/or a single damascene
pattern.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority to and the benefit of
Korean Patent Application No. 10-2004-0074498 filed in the Korean
Intellectual Property Office on Sep. 17, 2004, the entire contents
of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] a) Field of the Invention
[0003] The present invention relates to a manufacturing method of a
semiconductor device.
[0004] b) Description of the Related Art
[0005] During a manufacturing process of a semiconductor device, a
diffusion barrier is frequently formed on an interior wall of a
hole such as a contact hole or via hole, in order to prevent a
metal such as copper used for a metal line from diffusing into
underlying silicon and/or an adjacent oxide. The diffusion barrier
must have conductivity, and typical examples thereof are titanium
nitride (TiN), tungsten nitride (WN), and tantalum nitride
(TaN).
[0006] Recently, copper has frequently been used for metal lines in
semiconductor devices instead of aluminum, in order to improve
device characteristics, such as operating speed or resistance. This
copper has merits such as low resistivity and high melting point,
but it also has drawbacks as described below.
[0007] For example, copper has no fine protective layer such as
Al.sub.2O.sub.3, it shows poor adhesion to silicon dioxide
(SiO.sub.2), and it is difficult to dry etch. In addition, copper
has a diffusion coefficient about 106 times higher than that of
aluminum in silicon, and the diffused copper forms a deep energy
level between band gaps. In addition, copper also has a high
diffusion coefficient in SiO.sub.2, and accordingly, an insulating
property between the copper lines may deteriorate. As a result, the
high diffusion coefficient of Cu in silicon or SiO.sub.2 may
substantially deteriorate reliability of a semiconductor
device.
[0008] Therefore, in order to ensure sufficient reliability during
a copper line process, there is a need for a diffusion barrier that
can prevent copper from rapidly diffusing into silicon or
SiO.sub.2.
[0009] As above-described, the diffusion barrier plays an important
role in interconnections. Therefore, it is important to develop a
technique that is capable of forming a fine diffusion barrier. TaN,
for example, is thermodynamically stable with copper. Accordingly,
many methods have been developed to use a TaN thin film as a fine
diffusion barrier during the copper line manufacturing process.
[0010] TaN thin films generally have high thermal stability,
excellent adhesion to the oxide layer, and a desirable diffusion
barrier characteristic. Accordingly, TaN thin films are widely used
as a diffusion barrier. Generally, the TaN thin film is formed of a
TaN/Ta bi-layer with a thickness of 100 nm or more by a physical
vapor deposition (PVD) method.
[0011] As semiconductor devices have become smaller, Cu lines with
a width of 65 nm or less are desired. Accordingly, the TaN thin
film must have a thickness of less than 5 nm. However, according to
the PVD method, the TaN thin film generally cannot realize
sufficiently uniform step coverage at such thicknesses. In order to
overcome this non-uniform deposition and to acquire excellent step
coverage and a desirable diffusion barrier characteristic, an
atomic layer deposition (ALD) method has been developed.
[0012] The ALD method employs a precursor (for example, a
metal-organic precursor and a halogen compound such as TaCl.sub.5)
to form or deposit a TaN thin film. However, when the TaN thin film
is deposited by the ALD method employing the metal-organic
precursor, the TaN thin film may include a substantial amount of
carbon. In this case, a low film density and high resistivity
result, such that the copper lines may not have desired electric
characteristics.
[0013] Therefore, research has been undertaken to employ the
halogen compound such as TaCl.sub.5 as a precursor for the
diffusion barrier. However, in this case, impurities such as Cl may
cause corrosion to the copper lines such that reliability of the
semiconductor device may deteriorate.
[0014] The above information disclosed in this Background section
is only for enhancement of understanding of the background of the
invention, and therefore, it may contain information that does not
form information or prior art that may be known in this or any
other country to a person of ordinary skill in the art.
SUMMARY OF THE INVENTION
[0015] The present invention has been made in an effort to provide
a manufacturing method of a semiconductor device having advantages
of reducing impurities and increasing density of a TaN thin
film.
[0016] An exemplary method of manufacturing a semiconductor device
according to an embodiment of the present invention includes
forming a substrate having a plurality of predetermined structures
therein, and forming a TaN thin film on the substrate by
plasma-enhanced atomic layer deposition (PEALD) using a plasma gas
comprising a Ta precursor and a hydrogen source gas (e.g.,
H.sub.2). The substrate generally contains a plurality of
semiconductor devices (e.g., transistors, diodes, resistors,
capacitors, etc.) therein and/or thereon.
[0017] Another exemplary method of manufacturing a semiconductor
device according to an embodiment of the present invention includes
purging a reactor and a gas line, injecting a Ta precursor in the
reactor to deposit a Ta-containing layer on a substrate, purging
the reactor and the gas line again, supplying a hydrogen source gas
(e.g., H.sub.2 gas) by opening a hydrogen source gas valve
connected to the reactor and gas line, forming a TaN thin film by
supplying a plasma power to the reactor, and stopping the supply of
the plasma power and the hydrogen source gas.
[0018] The Ta precursor may be selected from among
pentakis(ethylmethylamino)tantalum (PEMAT),
tertbutylimido(trisdiethylamide)-tantalum (TBTDET),
pentakis(diethylamide)tantalum (PDEAT), and
pentakis(dimethylamide)tantalum (PDMAT).
[0019] The first and second purging steps of the reactor and gas
line may be respectively performed for 1 to 3 sec, and/or the
plasma power may be supplied for a length of time of from 11 to 13
sec.
[0020] An inert and/or nitrogen-containing gas (e.g., N.sub.2 gas)
may be further supplied to the reactor, and the plasma gas may
therefore further comprise an inert and/or nitrogen-containing
gas.
[0021] The TaN film may be deposited at a temperature of
250.degree. C. or higher.
[0022] The manufacturing method may further include forming a metal
line on the TaN thin film. The metal line may comprise copper,
aluminum, and/or tungsten.
[0023] The manufacturing method may further include depositing a
seed copper layer on the TaN thin film and forming a copper line on
the seed copper layer. The seed copper layer may be formed by PVD,
ALD, or a CVD method. Also, the manufacturing method may further
include depositing Ta on the TaN thin film, before depositing a
seed copper layer on the Ta and/or forming a copper line on the
seed copper layer.
[0024] The manufacturing method may further include forming a
copper line on the TaN thin film in a dual damascene or single
damascene pattern.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] FIG. 1 is a schematic diagram of an apparatus used in a
manufacturing method of a semiconductor device according to an
exemplary embodiment of the present invention, wherein the
apparatus employs the PEALD method to deposit a TaN thin film.
[0026] FIG. 2 is a depth profile of TaN thin films deposited by a
thermal decomposition ALD method, obtained by XPS-analyzing with
respect to various deposition temperatures.
[0027] FIG. 3 illustrates results obtained in TaN thin films
deposited by the thermal decomposition ALD method, in which certain
gas component ratios are varied and in which the results are
obtained by an AES analysis, assuming a total of component ratios
to be 100.
[0028] FIG. 4 illustrates a chemical composition analysis result
for various kinds of plasma gases used in plasma processing
performed for increasing density, decreasing resistivity and/or
removing impurities in the TaN thin film deposited using PEMAT.
[0029] FIG. 5 illustrates a variation of resistivity values of TaN
thin films deposited using various plasma gases.
[0030] FIG. 6 illustrates a variation of resistivity values
depending on deposition temperatures with respect to a TaN thin
film having a 320 .ANG. thickness after 400 cycles of plasma
processing when H.sub.2 is used as a plasma gas.
[0031] FIG. 7 illustrates a composition analysis result of TaN thin
films formed at various deposition temperatures using a plasma gas
containing H.sub.2, obtained by an AES analysis.
[0032] FIG. 8 illustrates step coverage of a TaN thin film
deposited on a substrate containing a single pattern having a via
hole with an opening width of 0.18 .mu.m and an aspect ratio of
6:1, at a deposition temperature of 300.degree. C., and by 200
cycles of plasma processing using an H.sub.2 plasma gas, which is
obtained by SEM analysis.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0033] With reference to the accompanying drawings, the embodiment
of the present invention will be described in order for those
skilled in the art to be able to implement the invention. As those
skilled in the art would realize, the described embodiments may be
modified in various different ways, all without departing from the
spirit or scope of the present invention.
[0034] To clarify multiple layers and regions, the thicknesses of
the layers are enlarged in the drawings. Like reference numerals
designate like elements throughout the specification. When it is
said that any part, such as a layer, film, area, or plate, is
deposited on another part, it means the part is directly on the
other part or above the other part with at least one intermediate
part. Further, if any part is said to be deposited directly on
another part, it means that there is no intermediate part, layer or
structure between the two parts.
[0035] Now, an embodiment of the present invention will be
described in detail with reference to the accompanying
drawings.
[0036] FIG. 1 is a schematic diagram of apparatus used in
manufacturing a semiconductor device according to an exemplary
embodiment of the present invention, where the apparatus employs
the PEALD method to deposit a TaN thin film.
[0037] Referring to FIG. 1, the thin film deposition apparatus
includes storage tanks 11, 12, 13, 14, an 16 for storing process
gases, mass flow controllers (MFCs) 21, 22, 23, 24, and 25, valves
30a and 30b for controlling the process gas(ses) flowing from the
storage tank, a reactor 1 for reacting the process gases controlled
by the MFCs and valves (e.g., to deposit a film onto a substrate in
the reactor), gas lines 17 in which these process gases flow, and
purge gas lines 18 for purging the reactor 1 and the gas line 17,
using the vacuum pump 9 before or after a reaction.
[0038] In this case, the reactor 1 includes a shower head 4 for
providing uniform flow 5 of the process gas (or gas mixture), and a
susceptor 2 for supporting a substrate 3 therein. Also, the reactor
1 is coupled with an RF power supplying apparatus 8 for supplying a
power. The RF power supplying apparatus 8 is also coupled with an
RF matching box 7 for controlling a periodic supply of power.
Accordingly, the plasma reaction can be synchronized to the gas
flow 5.
[0039] In a plasma-enhanced atomic layer deposition (PEALD) method
using this apparatus, first, the reactor 1 may form an oxide layer
with a thickness of about 1,000 .ANG. on the silicon substrate 3.
Silicon substrate 3 may have a diameter of 200 mm, 300 mm, etc.
[0040] In addition, the storage tank 16 supplies a Ta precursor
(e.g., pentakis(ethylmethylamino)tantalum, or PEMAT) through the
gas line 17 to the reactor 1. The Ta precursor (e.g.,
pentakis(ethylmethylamino)tantalum) is a metal-organic precursor,
and it may react with other processing gases introduced into the
reactor 1 or to be deposited on the oxide layer. In this case, a
TaN thin film may be formed on the upper surface of the oxide
layer. Alternatively, the TA precursor may comprise any
organometallic Ta compound having alkylimido and/or dialkylamido
groups bound thereto (e.g., of the formula
Ta(NR.sub.2).sub.x(.dbd.NR).sub.y, where R is an alkyl group having
6 or fewer (preferably 4 or fewer) carbon atoms and x+2y=5, y
generally being 0 or 1), such as
tertbutylimido(trisdiethylamide)tantalum (TBTDET),
pentakis(diethylamide)tantalum (PDEAT),
pentakis(dimethylamide)tantalum (PDMAT), etc.
[0041] When depositing the TaN thin film using a Ta precursor such
as PEMAT, the temperature is generally controlled in a range of
from 200.degree. C. to 350.degree. C. (preferably from 250.degree.
C. to 350.degree. C.). In addition, impurities may be removed from
the TaN thin film by plasma-processing the same using a hydrogen
source such as hydrogen gas, or a mixture of a hydrogen source and
a nitrogen source such as a mixed gas of hydrogen and nitrogen, to
reduce the resistivity and to increase the density of the thin
film. Alternatively, the hydrogen and/or nitrogen source may
comprise a substantially carbon- and oxygen-free compound such as
ammonia (NH.sub.3) or hydrazine (H.sub.2NNH.sub.2). In addition,
the hydrogen and/or nitrogen source may further include an inert
gas, such as He or Ar, etc.
[0042] The RF power supplying apparatus 7 is operated under a
plasma power of 300 W and a frequency of 13.56 MHz to generate
plasma. That is, depositing a TaN thin film using PEALD according
to the invention includes introducing a Ta precursor (e.g., PEMAT)
and forming a TaN thin film by plasma processing. PEALD generally
includes a plurality of cycles, wherein each cycle includes (1)
purging of the reactor and the gas line, (2) supplying a Ta
precursor and depositing a Ta-containing layer on the substrate,
(3) purging the reactor and the gas line, (4) introducing a
hydrogen and/or nitrogen source into the reactor (e.g., opening the
gas valves for H.sub.2 and N.sub.2), (5) supplying a plasma power
to the reactor and performing plasma processing, and (6) stopping
the plasma power and closing the gas valves. In one case, the
purging and Ta precursor supplying steps are performed for 2
seconds, and the plasma processing is performed for 12 seconds.
[0043] Now, the invention will be described in greater detail with
reference to FIGS. 2 to 8, in which the TaN thin film deposited
from a dialkylamidotantalum (PEMAT) precursor at a temperature
higher than 250.degree. C. by the PEALD method has excellent
resistivity, thin film component, binding energy, and step coverage
characteristics.
[0044] First, basic bonding properties of a TaN thin film are
analyzed using an X-ray photoelectron spectroscopy (XPS) method. In
this case, chemical components of the TaN thin films and the
bonding property thereof are analyzed according to deposition
temperatures of a thermal decomposition ALD method.
[0045] FIG. 2 is a depth profile of TaN thin films deposited by a
thermal decomposition ALD method, obtained by XPS-analysis with
respect to various deposition temperatures. Generally, it is known
that a TaN thin film has a binding energy of 21.5 eV and 26.5 eV.
It is also known that peaks appear at 21.9 eV for pure Ta (Ta
4f7/2), and at about 26.5 eV for tantalum oxide.
[0046] As shown in FIG. 2, according to the ALD method, peaks of
the TaN thin film are stably observed at a similar range of binding
energy. In addition, as the deposition temperature is increased,
tantalum (Ta) is combined with nitrogen instead of oxygen. That is,
according to the thermal decomposition ALD method, the binding
property of the TaN thin film shows that Ta binds with oxygen at a
deposition temperature of lower than 200.degree. C., and with
nitrogen at a deposition temperature of higher than 250.degree. C.
Therefore, the deposition processing generally should be performed
at a temperature higher than 250.degree. C. in order to obtain a
stable TaN thin film.
[0047] Now, impurities and compositions of Ta and N in the TaN thin
film are analyzed using an Auger electron spectroscopy (AES)
method. In this case, they are analyzed according to the deposition
temperatures and plasma gases. That is, a variation of binding
property with respect to the deposition temperature in the TaN thin
film may be observed by the AES analyzing results.
[0048] FIG. 3 illustrates a variation of component ratio of TaN
thin films deposited by the thermal decomposition ALD method, which
is obtained by an AES analysis assuming a total of component ratios
to be 100. As shown in FIG. 3, regarding the composition, as the
deposition temperature is increased, the oxygen content is
decreased, and the Ta content and the nitrogen content are
increased. This result is in concordance with the XPS analysis
result of FIG. 2. That is, at a deposition temperature of
250.degree. C. or higher, Ta and nitrogen are combined to generate
the TaN thin film (although, under certain conditions, the TaN thin
film may have sufficient conductivity properties for some
applications when formed at a temperature between 200.degree. C.
and 250.degree. C.).
[0049] FIG. 4 illustrates a chemical composition analysis result
for various kinds of plasma gases and gas mixtures used in plasma
processing the substrate having a Ta-containing layer thereon. Such
plasma processing is generally performed for increasing film
density and decreasing film resistivity by removing impurities in
the TaN thin film deposited using a dialkylamidotantalum precursor
such as PEMAT.
[0050] In FIG. 4, the TaN thin film is deposited at a deposition
temperature of 300.degree. C. over 300 cycles according to the
PEALD method. According to scanning electron microscopy (SEM)
analysis, the TaN thin film has a thickness of about 0.8 A during
each cycle, regardless of the particular plasma gas mixture.
[0051] When the plasma gas comprises a mixture of hydrogen and
nitrogen sources (e.g., a mixed gas of H.sub.2 and N.sub.2), the
TaN thin film contains impurities of oxygen and carbon at an atomic
percentage of 10% or less each (carbon being <<10 at. %), and
the nitrogen is at a relatively higher level. This is because, in
the plasma processing, carbon is replaced by nitrogen to increase
the nitrogen content, the replaced carbon bonds with hydrogen to
form volatile hydrocarbons (and/or alkylamines) that are easily
removed, and the oxygen impurity can be removed as H.sub.2O.
[0052] On the other hand, when only H.sub.2 gas is used as the
plasma gas, the TaN thin film has oxygen impurities at a level of
about 25 at. % and carbon impurities at about a 10 at. % level,
both of which are relatively higher in comparison with the case of
the mixed hydrogen and nitrogen source gasses, and nitrogen is
present in an atomic percentage of about 40%. Therefore, it is
understood that the impurities are more effectively removed from
the TaN thin film when plasma processing is performed using
source(s) of hydrogen and nitrogen (e.g., the mixed gas of H.sub.2
and N.sub.2).
[0053] FIG. 5 illustrates a variation of resistivity values of TaN
thin films deposited using various plasma gases. Resistivity in the
TaN thin film is measured using a 4 point probe method.
[0054] As shown in FIG. 5, when only hydrogen is used as the plasma
gas, the TaN thin film has impurities of oxygen and carbon at
relatively higher levels in comparison with using a mixed gas of
H.sub.2 and N.sub.2. However, the resistivity is considerably
reduced to 7,000.OMEGA.-cm. This is because the TaN phase generally
changes according to the nitrogen content. In more detail, when the
mixed gas of H.sub.2 and N.sub.2 is used as the plasma gas,
nitrogen can be replaced with carbon to form an fcc-TaN phase,
having a face-center edcubic structure.
[0055] The fcc-TaN phase has a crystalline structure by which a
resistivity may become more than 10,000.OMEGA.-cm. When only
hydrogen is used as the plasma gas, the TaN thin film has about 40%
nitrogen to form an hcp-Ta.sub.2N phase, that is, a Ta.sub.2N phase
of a hexagonal close-packed lattice structure.
[0056] According to the PVD method, the hcp-Ta.sub.2N has
resistivity of about 300.OMEGA.-cm. Accordingly, it is understood
that, when only hydrogen is used as the plasma gas according to an
exemplary embodiment of the present invention, the hcp-Ta.sub.2N
may have a higher resistivity than that of a conventional
hcp-Ta.sub.2N. This is because impurities such as oxygen may be
present.
[0057] FIG. 6 illustrates a variation of resistivity values
depending on deposition temperatures with respect to a TaN thin
film having a 320 .ANG. thickness after 400 cycles of plasma
processes when H.sub.2 is used as a plasma gas. As shown in FIG. 6,
the resistivity varies significantly according to the deposition
temperature. The TaN thin film has a low resistivity of
960.OMEGA.-cm when deposited at a temperature of about 350.degree.
C.
[0058] FIG. 7 shows composition analyses (obtained by AES analysis)
of TaN thin films formed at various deposition and/or processing
temperatures using an H.sub.2 plasma gas. As shown in FIG. 7, when
the TaN thin film is processed under an H.sub.2 gas plasma
atmosphere, the TaN thin film has a relatively uniform nitrogen
content (in a range of from 30% to about 40%), regardless of the
deposition temperature. However, the TaN thin film has a relatively
smaller oxygen content as the deposition temperature is increased
(from (a) to (d)), and Ta and carbon contents become larger as the
oxygen content becomes smaller.
[0059] From FIG. 6 and FIG. 7, it is understood that the
resistivity increase primarily depends on the oxygen content rather
than the carbon content in the TaN thin film. In addition, when
H.sub.2 is used as a plasma gas, the nitrogen content may be
constant regardless of the deposition temperature. Thus, the TaN
phase may also be constant regardless of the deposition
temperature.
[0060] FIG. 8 illustrates step coverage of a TaN thin film
deposited on a substrate having a single pattern thereon (e.g., a
via hole pattern having an opening width of 0.18 .mu.m and an
aspect ratio of 6:1), at a deposition temperature of 300.degree.
C., using 200 cycles of plasma processing and an H.sub.2 plasma
gas. The results in FIG. 8 were obtained by SEM analysis.
[0061] As shown in FIG. 8, the TaN thin film 10 has side coverage
at locations 52 and 53 in the via hole of about 95% and bottom
coverage at location 51 of about 80%. The TaN thin film has
excellent step coverage.
[0062] From the above description, the resistivity, composition,
binding property and step coverage characteristics of the TaN thin
film to be used as a diffusion barrier for a copper line with a
width of 65 nm or less in a semiconductor device is found to be as
described below.
[0063] From the XPS and AES analysis result, the TaN thin film
deposited by the thermal decomposition ALD method is found to have
a stronger Ta-N binding strength as the deposition temperature is
increased. However, according to the PEALD method, when the plasma
gas contains hydrogen and no nitrogen source, the TaN thin film has
a much better resistivity characteristic than in the case where the
plasma gas comprises H.sub.2 and N.sub.2. That is, the TaN thin
film has a low resistivity of 960.OMEGA.-cm when deposited at
350.degree. C. under an H.sub.2 gas plasma atmosphere. The
resistivity is mostly dependent on the oxygen content among the
impurities.
[0064] According to the PEALD method, the TaN thin film has
excellent step coverage of about 95% in the via-hole structure of a
size of 0.18 .mu.m and an aspect ratio of 6:1. Meanwhile, the TaN
thin film may be used as diffusion barrier such that a metal line
may be formed on the TaN thin film. These metal lines may comprise
copper, aluminum, or tungsten.
[0065] Now, a method for forming a copper line according to an
exemplary embodiment of the present invention will be described
below.
[0066] A TaN thin film is formed as described above, and a seed
copper layer may be deposited on the TaN thin film by a
conventional technique (e.g., electroplating). Copper lines are
then formed on the seed copper layer by a conventional technique
(e.g., PVD).
[0067] In addition, Ta may be deposited on the TaN thin film, prior
to depositing a seed copper layer on the Ta. The copper line may
then be formed on the seed copper layer by PVD, ALD, or CVD.
[0068] In addition, the copper line may be formed in a dual
damascene and/or a single damascene pattern. In other words, the
substrate may have an upper (or exposed) insulator layer containing
a predetermined dual damascene and/or a single damascene pattern
therein. In such a case, the TaN thin film may provide a diffusion
barrier function for the copper line of any pattern in the single
and dual damascene patterns.
[0069] According to an exemplary embodiment of the present
invention, the method of manufacturing a semiconductor device
generally employs a PEALD method, using an organometallic Ta
precursor such as PEMAT to form a TaN thin film. As a result, a
conformal TaN diffusion barrier may be formed at a temperature
higher than 250.degree. C. so that impurities are reduced and
density is increased in the TaN thin film.
[0070] While this invention has been described in connection with
what is presently considered to be practical exemplary embodiments,
it is to be understood that the invention is not limited to the
disclosed embodiments, but, on the contrary, is intended to cover
various modifications and equivalent arrangements included within
the spirit and scope of the appended claims.
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